In reviewing the various papers on power controls which have been read before the Society in the past few years, it soon became apparent that, considering the broad issues involved, there is little to add to what has already been said.

D. J. Lyons admitted, somewhat reluctantly, that power controls might become a necessity on aircraft designed to fly for extended periods in the transonic region.

The 855th Lecture to be given before the Royal Aeronautical Society, “ Fuel Systems for Turbine-Engined Aircraft ” by Mr. J. E. Walker, A.F.R.Ae.S., was read under the auspices of the Luton Branch of the Society on the 24th April 1952 at Luton.

Some liberties have been taken with the contents of the lecture in relation to the title. Firstly, it is proposed to examine safety in general, for only by this means can airworthiness be seen in its true perspective. Secondly, some trends in airworthiness and inter-related operational matters will be discussed. Finally, crashworthiness is dealt with at some length.

In choosing a title for this paper, the words “ operational research ” might have been preferable to “ production research ” in the sense that “ operations ” refer to the strategic deployment of all the forces at the disposal of management, but to most engineers they would imply research into manufacturing processes only.

There are two parts of this paper, the first dealing with Servicing and the second with Reliability. Although they are connected in many ways, and indeed servicing has been taken to mean checking parts which might be unreliable, it is convenient to separate them.

A practical factor of increasing importance is the burial of the accessory machines in modern aeroplanes.

Compared with, say, a plough, the parts of Blériot's Anzani engine might be thought to be dangerously concealed; dangerous, that is to say, if its working depended on any condition of the internal parts which could be judged when looked at. But the Anzani engine was simplicity itself, compared with any modern machine, even an accessory machine, and these machines are usually covered by, or rather entangled in, the structure.

In assessing the true extent of technical development of any kind the mind naturally seeks a standard for comparison. When considering structural development the standard chosen could well be that associated with the end of the Second World War. In preparing this paper, therefore, it appeared profitable, and certainly it has been extremely interesting for the author, to review the structure of some of the aircraft then in quantity production.

The Eighth British Commonwealth and Empire Lecture was given by Mr. R. E. Hardingham, O.B.E., F.R.Ae.S., M.S.L.A.E., before the Royal Aeronautical Society on 2nd October 1952 at the Institution of Mechanical Engineers, Storeys Gate, S.W.I. The audience included a number of distinguished guests, among them visitors from overseas and representatives of the Divisions of the Society.

Mr. G. H. Dowty, F.R.Ae.S., President of the Society, at whose suggestion the British Commonwealth and Empire Lectures were started in 1945, presided over the meeting. After welcoming the guests Mr. Dowty introduced Mr. Hardingham, outlining his career briefly. Mr. Hardingham was one of the original apprentices at the Royal Aircraft Establishment and in 1921 joined the de Havilland Aircraft Co. Ltd. Later he served for three years with the Air Ministry during which period he was associated with the Aeronautical Inspection Directorate and the Directorate of Technical Development. He joined the Air Registration Board on its formation in 1937, becoming Principal Surveyor in 1945. In 1947 he was appointed Secretary and Chief Executive and that same year became an Officer of the Order of the British Empire. Mr. Hardingham has represented the United Kingdom at a number of International Conferences.

The 837th Lecture to be given before the Royal Aeronautical Society, was delivered at the Institution of Civil Engineers, Great George Street, London, S.W.I, on 6th December 1951. Mr. G. R. Edwards, M.B.E., F.R.Ae.S., Vice-President of the Society, presided and introduced the Lecturer, Dr. J. Seddon, A.F.R.Ae.S., of the Royal Aircraft Establishment.

A rapid method is developed for estimating the profile drag of an aerofoil with a known transition point position. The results are in good agreement with previous calculations.

A previous paper was concerned with the uniform finite bending of a flat rectangular elastic plate about an axis parallel to one of its pairs of opposite edges. Expressions were obtained for the shape assumed by sections of the plate containing the axis of curvature, and the applied bending moment. In the present paper the work is extended to deal with a plate having shallow regular corrugations of arbitrary shape running along it at right angles to the axis of curvature. Such a plate may be of interest as it exhibits the type of instability characteristic of curved thin-walled members. Its solution can be derived quickly from the previous work.

In the past attempts have been made to correlate the estimated load variations which the component will experience during a stipulated lifetime (in hours) with estimations of the fatigue strength (in cycles of loading) for typical structural components, such as wing spar boom joints, riveted joints, and so on. The trend of thinking so far has been that one should design for a certain fatigue life. In this paper it is shown that, even with the most careful attention given to the detail design of aluminium alloy components, it is not possible to attain what has been regarded hitherto as the minimum acceptable fatigue strength for typical structures, i.e. 2 x 106 cycles of 1g±7½ per cent. ultimate strength of the structure, based on present British Civil Airworthiness Requirements (Reserve Factor 1.0). There is no implied criticism of the criterion which is an ideal one, and if structures attained the criterion then the fatigue life would be adequate.